Chemical mechanical polishing pad having electrospun polishing layer

ABSTRACT

Chemical mechanical polishing pads having an electrospun polishing layer are provided, wherein the electrospun polishing layer has a polishing surface that is adapted for polishing a semiconductor substrate. Also provided are methods of making such chemical mechanical polishing pads and for using them to polish semiconductor substrates.

The present invention relates generally to the field of polishing padsfor chemical mechanical polishing. In particular, the present inventionis directed to chemical mechanical polishing pads having an electrospunpolishing layer and to methods of making and using the same.

Chemical mechanical planarization, or chemical mechanical polishing(CMP), is a common technique used to planarize or polish workpieces suchas semiconductor wafers. In conventional CMP, a wafer carrier, orpolishing head, is mounted on a carrier assembly. The polishing headholds the wafer and positions the wafer in contact with a polishinglayer of a polishing pad that is mounted on a table or platen within aCMP apparatus. The carrier assembly provides a controllable pressurebetween the wafer and polishing pad. Simultaneously, a polishing mediumis optionally dispensed onto the polishing pad and is drawn into the gapbetween the wafer and polishing layer. To effect polishing, thepolishing pad and wafer typically rotate relative to one another. As thepolishing pad rotates beneath the wafer, the wafer sweeps out atypically annular polishing track, or polishing region, wherein thewafer's surface directly confronts the polishing layer. The wafersurface is polished and made planar by chemical and mechanical action ofthe polishing layer and polishing medium on the surface.

For conventional polishing pads, pad surface “conditioning” or“dressing” is critical to maintaining a consistent polishing surface forstable polishing performance. Over time the polishing surface ofconventional polishing pads wears down, smoothing over the texture ofthe polishing surface—a phenomenon called “glazing”. The origin ofglazing is plastic flow of the polymeric material due to frictionalheating and shear at the points of contact between the pad and theworkpiece. Additionally, debris from the CMP process can clog thesurface voids as well as the channels through which polishing mediumflows across the polishing surface. When this occurs, the polishing rateof the CMP process decreases, and this can result in non-uniformpolishing between wafers or within a wafer. Conditioning creates a newtexture on the polishing surface useful for maintaining the desiredpolishing rate and uniformity in the CMP process.

Conventional polishing pad conditioning is achieved by abrading thepolishing surface mechanically with a conditioning disk. Theconditioning disk has a rough conditioning surface typically comprisedof imbedded diamond points. The conditioning disk is brought intocontact with the polishing surface either during intermittent breaks inthe CMP process when polishing is paused (“ex situ”), or while the CMPprocess is underway (“in situ”). Typically the conditioning disk isrotated in a position that is fixed with respect to the axis of rotationof the polishing pad, and sweeps out an annular conditioning region asthe polishing pad is rotated. The conditioning process as described cutsmicroscopic furrows into the pad surface, both abrading and plowing thepad material and renewing the polishing texture.

Conventional polishing pads have less than optimal texture. For example,Reinhardt et al., in U.S. Pat. No. 5,578,362, discloses the use ofpolymeric spheres to introduce texture into a polyurethane polishingpad. The conditioning of such pads is typically not exactlyreproducible. The diamonds on a conditioning disk become dulled with usesuch that the conditioner must be replaced after a period of time;during its life the effectiveness of the conditioner thus continuallychanges. Conditioning also contributes greatly to the wear rate of a CMPpad. It is common for about 95% of the wear of a pad to result from theabrasion of the diamond conditioner and only about 5% from contact withworkpieces.

Accordingly, there is a continuing need for CMP polishing pads having apolishing surface that can be renewed with a minimum of abrasiveconditioning (i.e., that are self renewing); and hence, exhibit anextended useful pad life.

In one aspect of the present invention, there is provided a chemicalmechanical polishing pad for polishing semiconductor substrates,comprising: an electrospun polishing layer; wherein the electrospunpolishing layer has a polishing surface that is adapted for polishing asemiconductor substrate.

In another aspect of the present invention, there is provided a methodfor producing a chemical mechanical polishing pad, comprising:electrostatically spinning at least one liquid spinning compositionthrough at least one spinneret to form spun fibers and collecting thespun fibers on a target to provide an electrospun polishing layer havinga polishing surface, wherein the polishing surface is adapted forpolishing a semiconductor substrate.

In another aspect of the present invention, there is provided a methodfor producing a chemical mechanical polishing pad, comprising: providingan electrospun polishing layer having a polishing surface and athickness of ≧10 mils prepared by electrostatically spinning at leastone liquid spinning composition through at least one spinneret into spunfibers and collecting the spun fibers on a target, wherein the liquidspinning composition is an organic material; and, incorporating textureinto the polishing surface.

In another aspect of the present invention, there is provided a methodof polishing a semiconductor substrate, comprising: (a) providing achemical mechanical polishing pad comprising an electrospun polishinglayer, wherein the electrospun polishing layer has a thickness of ≧10mils and wherein the electrospun polishing layer has a polishingsurface; (b) providing a semiconductor substrate; and, (c) creatingdynamic contact between the polishing surface and the semiconductorsubstrate to polish a surface of the semiconductor substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a multi-head, multi-spinneretapparatus used to produce an electrospun polishing layer.

FIG. 2 is a scanning electron micrograph of an electrospun polishinglayer.

FIG. 3 is a scanning electron micrograph of an electrospun polishinglayer.

FIG. 4 is a side perspective representation of a chemical mechanicalpolishing pad of one embodiment of the present invention.

FIG. 5 is a top plan view of a chemical mechanical polishing pad of oneembodiment of the present invention with a groove pattern in thepolishing surface.

FIG. 6 is a top plan view of a chemical mechanical polishing pad of oneembodiment of the present invention with a groove pattern in thepolishing surface, wherein the polishing pad exhibits a pad outer radiusR_(O) and a base radius R_(B); and 8 curved grooves.

FIG. 7 is a top plan view of a chemical mechanical polishing pad of oneembodiment of the present invention with a groove pattern in thepolishing surface, wherein the polishing pad exhibits a pad outer radiusR_(O); a base radius R_(B); and 8 curved grooves.

FIG. 8 is a top plan view of a chemical mechanical polishing pad of oneembodiment of the present invention with a groove pattern in thepolishing surface, wherein the polishing pad exhibits a pad outer radiusR_(O) and a base radius R_(B).

FIG. 9 is a close-up view of a groove segment of groove 404 of FIG. 5.

DETAILED DESCRIPTION

The term “thickness” as used herein and in the appended claims inreference to an electrospun polishing layer having a polishing surfacemeans the average actual thickness of the electrospun polishing layermeasured in a direction normal to the polishing surface.

The term “polishing medium” as used herein and in the appended claimsencompasses particle-containing polishing solutions andnon-particle-containing solutions, such as abrasive-free andreactive-liquid polishing solutions.

The term “substantially circular cross section” as used herein and inthe appended claims in reference to an electrospun polishing layer meansthat the longest radius, r, of the cross section from the central axisto the outer periphery of the electrospun polishing layer is ≦20% longerthan the shortest radius, r, of the cross section from the central axisto the outer periphery of the electrospun polishing layer. (See FIG. 4).

The term “poly(urethane)” as used herein and in the appended claimsencompasses (a) polyurethanes formed from the reaction of (i)polyisocyanates and (ii) polyols; and, (b) poly(urethane) formed fromthe reaction of (i) polyisocyanates with (ii) polyols and (iii) water,polyamines or a combination of water and polyamines.

The term “circumference fraction grooved” or “CF” as used herein and inthe appended claims is defined by the following formula:

${CF} = \left\{ \frac{\left( {{{Portion}\mspace{14mu} {of}\mspace{14mu} {circumference}\mspace{14mu} {at}\mspace{14mu} a\mspace{14mu} {given}\mspace{14mu} {radius}},R,{{that}\mspace{14mu} {lies}\mspace{14mu} {across}\mspace{14mu} {any}\mspace{14mu} {groove}}} \right)}{\left( {{{Full}\mspace{14mu} {circumference}\mspace{14mu} {at}\mspace{14mu} {the}\mspace{14mu} {given}\mspace{14mu} {radius}},R} \right)} \right\}$

Note that if CF is constant as a function of radius for an electrospunpolishing layer of a given chemical mechanical polishing pad, then thefractional portion of the polishing surface of the electrospun polishinglayer that is grooved (or ungrooved) at a given radius will also beconstant as a function of radius.

In some embodiments of the present invention, the chemical mechanicalpolishing pad for polishing semiconductor substrates, comprises: anelectrospun polishing layer, wherein the electrospun polishing layer hasa polishing surface that is adapted for polishing a semiconductorsubstrate and wherein the polishing surface is self renewing. In someaspects of these embodiments, the chemical mechanical polishing pad doesnot require abrasive conditioning of the polishing surface to facilitatepolishing of multiple semiconductor substrates. That is, the electrospunpolishing layer having a polishing surface facilitates the successivepolishing of multiple semiconductor substrates with similar polishingcharacteristics without the need to periodically condition the polishingsurface using abrasive conditioning techniques. The self renewing aspectof the polishing surface of the electrospun polishing layer results inan extended pad life.

In some embodiments of the present invention, the electrospun polishinglayer comprises electrostatically spun fibers. The chemical and physicalproperties of the electrospun polishing layer can be specificallyengineered for particular chemical mechanical polishing operationsthrough the selection of the liquid spinning composition or compositionsused to prepare the spun fibers and through adaptations of the spinningprocess. In some aspects of these embodiments, the electrospun polishinglayer comprises spun fibers having a single composition, wherein thecomposition comprises a mixture of one or more components combined toform a liquid spinning composition, wherein each component contributes aparticular characteristic or group of characteristics to the electrospunpolishing layer formed therefrom. In some aspects of these embodiments,the electrospun polishing layer comprises spun fibers having more thanone composition. In some aspects of these embodiments, spun fibershaving different compositions are simultaneously deposited to form theelectrospun polishing layer, wherein the electrospun polishing layercomprises an intimately intermingled mass of spun fibers havingdifferent compositions. In some aspects of these embodiments, spunfibers having different compositions are deposited non-simultaneously toform the electrospun polishing layer, wherein the electrospun polishinglayer comprises a multiplicity of layers of different spun fibercomposition. In some aspects of these embodiments, spun fibers havingdifferent composition are deposited both simultaneously andnon-simultaneously to form the electrospun polishing layer, wherein theelectrospun polishing layer comprises a multiplicity of layers, whereinsome of the layers comprise an intimately intermingled mass of spunfibers having different compositions and wherein some of the layerscomprise spun fibers having a single composition.

In some embodiments of the present invention, the electrospun polishinglayer comprises electrostatically spun fibers, wherein the spun fibersare formed from a liquid spinning composition. In some aspects of theseembodiments, the liquid spinning composition comprises a polymer melt, aliquid monomer, a solution, a dispersion or a suspension. In someaspects of these embodiments, the liquid spinning composition comprisesa fiber forming thermoplastic. In some aspects of these embodiments, thefiber forming thermoplastic is selected from poly(urethane), polyurea,polyamide, polyvinyl chloride, polyacrylonitrile, polyethylene oxide,polyolefin, poly(alkyl)acrylate, protein, polysaccharide, polylactateand combinations thereof. In some aspects of these embodiments, theliquid spinning composition comprises a poly(urethane), a polyvinylchloride or a combination thereof. In some aspects of these embodiments,the liquid spinning composition comprises a combination of polyurethanesand polyvinyl chloride.

In some embodiments of the present invention, the electrospun polishinglayer comprises electrostatically spun fibers, wherein the fibers have adiameter selected to provide the desired polishing properties to theelectrospun polishing layer. In some aspects of these embodiments, theelectrospun polishing layer comprises electrostatically spun fibers,wherein the fibers have a diameter of 10 to 2,000 nm, preferably 50 to2,000 nm; more preferably 100 to 2,000 nm. In some aspects of theseembodiments, the electrospun polishing layer comprises electrostaticallyspun organic fibers, wherein the fibers have a diameter of 10 to 2,000nm; preferably 50 to 2,000 nm; more preferably 100 to 2,000 nm. In someembodiments of the present invention, the diameter of theelectrostatically spun fibers is manipulated by varying at least one ofthe size or shape of a spinneret nozzle through which the fibers arespun, the distance between a spinneret and a target, and an appliedelectrostatic potential across a spinneret and a target.

In some embodiments of the present invention, the electrospun polishinglayer comprises electrostatically spun fibers, wherein the fibers aremulticomponent fibers exhibiting any type of cross-section, including,for example, sheath/core configurations, side by side configurations,pie wedge configurations, segmented ribbon configurations, segmentedcross configurations, tipped trilobal configurations and conjugateconfigurations. In some aspects of these embodiments, the multicomponentfibers include components derived from different liquid spinningcompositions.

In some embodiments of the present invention, the electrospun polishinglayer has an average pore size of ≦5 μm. In some aspects of theseembodiments, the electrospun polishing layer has an average pore size of≦2 μm. In some embodiments of the present invention, the average poressize is manipulated by, for example, varying a spinneret to targetdistance, varying a relative speed of movement between a spinneret and atarget in equidistant parallel planes, varying a relative direction ofmovement between a spinneret and a target in equidistant parallelplanes, varying a nozzle size or nozzle shape of a spinneret, varying anelectrostatic potential applied across a spinneret and a target, andcombinations thereof.

In some embodiments of the present invention, the electrospun polishinglayer exhibits a polishing surface and a thickness (measured in adirection normal to the polishing surface) of ≧5 mils; preferably ≧10mils; more preferably ≧20 mils. In some aspects of these embodiments,the electrospun polishing layer exhibits a thickness selected from 5 to300 mils; preferably 10 to 300 mils; more preferably 30 to 200 mils;still more preferably 30 to 150 mils; yet still more preferably 30 to125 mils and most preferably 40 to 120 mils.

In some embodiments of the present invention, the electrospun polishinglayer is subjected to post spinning treatment to fine tune its polishingproperties. In some aspects of these embodiments, the electrospunpolishing layer is treated to modify its hydrophobicity, tensilestrength, compressibility, total void volume, thermal stability,chemical resistance, surface area, or chemical functionality (e.g., toenhance adhesion between adjacent layers in the chemical mechanicalpolishing pad; to affect interactions between the electrospun polishinglayer and a semiconductor substrate being polished; to affectinteractions between the electrospun polishing layer and a polishingmedium used in combination therewith). In some aspects of theseembodiments, the electrospun polishing layer is treated with a binder.In some aspects of these embodiments, the electrospun polishing layer isheated to facilitate point bonding of the spun fibers. In some aspectsof these embodiments, the electrospun polishing layer is compressed andheated to simultaneously facilitate point bonding of the spun fibers anda reduction in the total void volume within the electrospun polishinglayer. In some aspects of these embodiments, the total void volumewithin the formed electrospun polishing layer is tailored by modifyingthe degree of entanglement of the spun fibers.

In some embodiments of the present invention, the electrospun polishinglayer exhibits voids within the electrospun polishing layer. In someaspects of these embodiments, the total void volume within theelectrospun polishing layer comprises 0.2 to 80 vol % of the electrospunpolishing layer. In some aspects of these embodiments, the total voidvolume comprises 0.3 to 80 vol % of the electrospun polishing layer. Insome aspects of these embodiments, the total void volume comprises 0.55to 70 vol % of the electrospun polishing layer. In some aspects of theseembodiments, the total void volume comprises 0.6 to 60 vol % of theelectrospun polishing layer.

In some embodiments of the present invention, the electrospun polishinglayer comprises a filler material. In some aspects of these embodiments,the filler material is selected from inorganic electrolytes, organicelectrolytes, water soluble inorganic substances, water soluble organicsubstances, water insoluble inorganic substances and water insolubleorganic substances. In some aspects of these embodiments, the fillermaterial comprises an organometallic. In some aspects of theseembodiments, the filler material comprises at least one non-electrospunfiber. In some aspects of these embodiments, the non-electrospun fiberis selected from natural fibers, synthetic fibers, inorganic fibers,combinations and blends thereof. The at least one non-electrospun fibermay be of any denier; may be a multi- or mono-filaments; may be falsetwisted or twisted; may incorporate multiple denier filaments into asingle yarn through twisting or melting; may be a multicomponent fiberexhibiting any type of cross-section, including, for example,sheath/core configurations, side by side configurations, pie wedgeconfigurations, segmented ribbon configurations, segmented crossconfigurations, tipped trilobal configurations and conjugateconfigurations. In some aspects of these embodiments, thenon-electrospun fiber is electrically conductive.

In some embodiments of the present invention, the electrospun polishinglayer comprises non-electrospun regions. In some aspects of theseembodiments, the electrospun polishing layer comprises an island orislands of randomly oriented spun fibers within a foam material, a filmor a non-woven material. In some aspects of these embodiments, theelectrospun polishing layer comprises a region or regions of randomlyoriented spun fibers and regions of a foam material, a film or anon-woven material. In some aspects of these embodiments, theelectrospun polishing layer is tailored to exhibit regions that promotemore aggressive polishing and regions that promote buffing.

In some embodiments of the present invention, the chemical mechanicalpolishing pad comprises an electrospun polishing layer and a base layer.In some aspects of these embodiments, the base layer is selected from afoam material, a film and a textile non-woven material. In some aspectsof these embodiments, the base layer is selected from an open cell foammaterial, a closed cell foam material and a foam material having acombined open cell and closed cell structure. In some aspects of theseembodiments, the base layer is an electrospun material. In some aspectsof these embodiments, the base layer is a film. In some aspects of theseembodiments, the base layer is a water impermeable film.

In some embodiments of the present invention, the chemical mechanicalpolishing pad further comprises a base layer and at least one additionallayer interposed between the base layer and the electrospun polishinglayer. In some aspects of these embodiments, the base layer and the atleast one additional layer are independently selected from a foammaterial, a film and a textile non-woven material. In some aspects ofthese embodiments, the base layer is selected from an open cell foammaterial, a closed cell foam material and a foam material having acombined open cell and closed cell structure. In some aspects of theseembodiments, the at least one additional layer is selected from an opencell foam material, a closed cell foam material and a foam materialhaving a combined open cell and closed cell structure. In some aspectsof these embodiments, the at least one additional layer is a film. Insome aspects of these embodiments, the at least one additional layer isa water impermeable film. In some aspects of these embodiments, the baselayer is a textile non-woven material. In some aspects of theseembodiments, the base layer is an electrospun material. In some aspectsof these embodiments, the at least one additional layer is a textilenon-woven material. In some aspects of these embodiments, the at leastone additional layer is an electrospun material. In some aspects ofthese embodiments, the base layer and the at least one additional layerboth comprise an electrospun material.

In some embodiments of the present invention, the chemical mechanicalpolishing pad comprises an electrospun polishing layer, a base layerand, optionally, at least one additional layer interposed between theelectrospun polishing layer and the base layer. In some aspects of theseembodiments, the chemical mechanical polishing pad includes at least oneadditional layer interposed between the electrospun polishing layer andthe base layer. In some aspects of these embodiments, the various layersare interfaced together using an adhesive. In some aspects of theseembodiments, the adhesive is selected from pressure sensitive adhesives,hot melt adhesives, contact adhesives and combinations thereof. In someaspects of these embodiments, the adhesive is a hot melt adhesive. Insome aspects of these embodiments, the adhesive is a contact adhesive.In some aspects of these embodiments, the adhesive is a pressuresensitive adhesive.

In some embodiments of the present invention, the chemical mechanicalpolishing pad is adapted to be interfaced with a platen of a polishingmachine. In some aspects of these embodiments, the chemical mechanicalpolishing pad is adapted to be affixed to the platen. In some aspects ofthese embodiments, the chemical mechanical polishing pad is adapted tobe affixed to the platen using at least one of an adhesive and a vacuum.In some aspects of these embodiments, the chemical mechanical polishingpad is adapted to be affixed to the platen using at least one of apressure sensitive adhesive and a vacuum.

In some embodiments of the present invention, the chemical mechanicalpolishing pad used has an electrospun polishing layer having a polishingsurface exhibiting texture. In some aspects of these embodiments, thepolishing surface of chemical mechanical polishing pads exhibit texturein the form of one or more grooves. There are several reasons forincorporating grooves in the polishing surface of a chemical mechanicalpolishing pad, including: (A) to prevent hydroplaning of the substratebeing polished across the surface of the polishing pad—(if the pad iseither ungrooved or unperforated, a continuous layer of polishing mediumcan exist between the substrate and the pad, preventing uniform intimatecontact and significantly reducing removal rate); (B) to ensure thatpolishing medium is uniformly distributed across the pad surface andthat sufficient polishing medium reaches the center of thesubstrate—(this is especially important when polishing reactive metalssuch as copper, in which the chemical component of the polishing is ascritical as the mechanical; uniform polishing medium distribution acrossthe substrate is required to achieve the same polishing rate at thecenter and edge of the substrate; however, the thickness of thepolishing medium layer should not be so great as to prevent directpad-substrate contact); (C) to control both the overall and localizedstiffness of the polishing pad—(this controls polishing uniformityacross the substrate surface and also the ability of the pad to levelfeatures of different heights to give a highly planar surface); (D) toact as channels for the removal of polishing debris from the padsurface—(a build-up of debris increases the likelihood of scratches andother defects); and (E) to act as a vacuum break to facilitateseparation of the chemical mechanical polishing pad from a semiconductorsubstrate being polished therewith.

Note that one factor that determines the polishing pad life for groovedpolishing pad is the depth of the grooves. That is, acceptable polishingperformance is possible only until the polishing pad has worn to thepoint where the grooves have insufficient remaining depth to effectivelydistribute polishing medium, remove polishing wastes and preventhydroplaning. Accordingly, it should be apparent that deeper grooves cancorrelate to a longer polishing pad life. It should also be apparentthat an initial electrospun polishing layer thickness exceeding aminimum is desirable to provide a commercially useful pad life.Preferably, the initial electrospun polishing layer thickness is ≧10mils.

In some embodiments of the present invention, the electrospun polishinglayer has a polishing surface exhibiting texture. In some aspects ofthese embodiments, the texture is designed to alleviate at least one ofhydroplaning; to influence polishing medium flow; to modify thestiffness of the polishing layer; to reduce edge effects; to facilitatethe transfer of polishing debris away from the area between thepolishing surface and the substrate; and to facilitate separation of thechemical mechanical polishing pad from a semiconductor substrate. Insome aspects of these embodiments, the texture comprises at least onegroove. In some aspects of these embodiments, the at least one groovehas a groove depth of ≧20 mils. In some aspects of these embodiments,the at least one groove has a depth of 20 to 100 mils. In some aspectsof these embodiments, the at least one groove has a groove depth of 20to 60 mils. In some aspects of these embodiments, the at least onegroove has a groove depth of 20 to 50 mils.

In some embodiments of the present invention, the electrospun polishinglayer has a polishing surface exhibiting texture, wherein the texturecomprises a groove pattern and wherein the groove pattern comprises atleast two grooves. In some aspects of these embodiments, the electrospunpolishing layer exhibits a texture comprising a groove pattern thatcomprises at least two grooves having a depth of ≧15 mils; a width of≧10 mils and a pitch of ≧50 mils. In some aspects of these embodiments,the groove pattern comprises at least two grooves having a depth of ≧20mils; a width of ≧15 mils and a pitch of ≧70 mils. In some aspects ofthese embodiments, the groove pattern comprises at least two grooveshaving a depth of ≧20 mils; a width of ≧15 mils and a pitch of ≧90 mils.

In some embodiments of the present invention, the electrospun polishinglayer exhibits a texture comprising a groove pattern. In some aspects ofthese embodiments, the groove pattern comprises at least one groove. Insome aspects of these embodiments, the groove pattern comprises aplurality of grooves. In some aspects of these embodiments, the at leastone groove is selected from curved grooves, straight grooves andcombinations thereof. In some aspects of these embodiments, the groovepattern is selected from a groove design including, for example,concentric grooves (which may be circular or spiral), curved grooves,cross-hatch grooves (e.g., arranged as an X-Y grid across the padsurface), other regular designs (e.g., hexagons, triangles), tire-treadtype patterns, irregular designs (e.g., fractal patterns), andcombinations thereof. In some aspects of these embodiments, the groovepattern is selected from random, concentric, spiral, cross-hatched, X-Ygrid, hexagonal, triangular, fractal and combinations thereof. In someaspects of these embodiments, the groove profile is selected fromrectangular with straight side-walls or the groove cross-section may be“V”-shaped, “U”-shaped, triangular, saw-tooth, and combinations thereof.In some aspects of these embodiments, the groove pattern is a groovedesign that changes across the polishing surface. In some aspects ofthese embodiments, the groove design is engineered for a specificapplication. In some aspects of these embodiments, the groove dimensionsin a specific design may be varied across the pad surface to produceregions of different groove densities. In some aspects of theseembodiments, at least one groove in the groove pattern has an initialgroove depth of ≧20 mils. In some aspects of these embodiments, at leastone groove in the groove pattern has an initial depth of 20 to 100 mils.In some aspects of these embodiments, at least one groove in the groovepattern has an initial groove depth of 20 to 60 mils. In some aspects ofthese embodiments, at least one groove in the groove pattern has aninitial groove depth of 20 to 50 mils.

In some embodiments of the present invention, the electrospun polishinglayer exhibits a texture comprising a groove pattern, wherein the groovepattern comprises at least one groove, wherein CF remains within 25%,preferably within 10%, more preferably within 5% of its average value asa function of an electrospun polishing layer radius, R, in an areaextending from an outer radius, R_(O), of a polishing surface of anelectrospun polishing layer a majority distance to an origin, O, at acenter of the polishing surface. In some aspects of these embodiments,CF remains within 25%, preferably within 10%, more preferably within 5%of its average value as a function of the electrospun polishing layerradius, R, in an area extending from a base radius, R_(B), to an outerradius, R_(O). (See, e.g., FIG. 5).

In some embodiments of the present invention, the chemical mechanicalpolishing pad comprises an electrospun polishing layer having apolishing surface exhibiting a texture selected from at least one ofperforations and grooves. In some aspects of these embodiments, theperforations can extend from the polishing surface part way or all ofthe way through the thickness of the electrospun polishing layer.

In some embodiments of the present invention, the chemical mechanicalpolishing pad has at least one of perforations that extend therethrough;conductive-lined grooves; an incorporated conductor, such as, conductivefibers, conductive network, metal grid or metal wire; which cantransform the chemical mechanical polishing pad into an eCMP(“electrochemical mechanical planarization”) polishing pad.

In some embodiments of the present invention, the chemical mechanicalpolishing pad has a central axis and is adapted for rotation about thecentral axis. (See FIG. 4). In some aspects of these embodiments, theelectrospun polishing layer 210 of the chemical mechanical polishing padis in a plane substantially perpendicular to the central axis 212. Insome aspects of these embodiments, the electrospun polishing layer 210is adapted for rotation in a plane that is at an angle, γ, of 80 to 100°to the central axis 212. In some aspects of these embodiments, theelectrospun polishing layer 210 is adapted for rotation in a plane thatis at an angle, γ, of 85 to 95° to the central axis 212. In some aspectsof these embodiments, the electrospun polishing layer 210 is adapted forrotation in a plane that is at an angle, γ, of 89 to 91° to the centralaxis 212. In some aspects of these embodiments, the electrospunpolishing layer 210 has a polishing surface 214 that has a substantiallycircular cross section perpendicular to the central axis 212. In someaspects of these embodiments, the radius, r, of the cross section of thepolishing surface 214 perpendicular to the central axis 212 varies by≦20% for the cross section. In some aspects of these embodiments, theradius, r, of the cross section of the polishing surface 214perpendicular to the central axis 212 varies by ≦10% for the crosssection.

FIG. 5 provides a top plan view of a chemical mechanical polishing pad400 of some embodiments of the present invention, wherein the polishingpad 400 has a texture comprising a groove pattern that comprises atleast one groove 404. The polishing pad 400 has an outer radius R_(O)and a polishing surface 402 with at least one groove 404 formed therein.Although only a single groove 404 is depicted in FIG. 5, the groovepattern can comprise two or more grooves 404. (See, e.g., FIGS. 6-8).The polishing pad radius R is measured from an origin O at the center ofthe polishing surface 402. A circle C_(R) (dashed line) drawn at radiusR with a circumference 2πR is also shown in FIG. 5. The outer radius ofpolishing pad 400 is R_(O). Groove 404 extends from base radius R_(B) toouter radius R_(O), which defines the outer periphery 406 of polishingsurface 402. In some aspects of these embodiments, the groove(s) 404extend from base radius R_(B) to outer periphery 406 (as depicted inFIGS. 5-8). In some aspects of these embodiments, the groove(s) 404extend from a point between the origin O and the base radius R_(B) toouter periphery 406. In some aspects of these embodiments, the groove(s)404 extend from origin O to outer periphery 406. FIG. 9 depicts aclose-up view of a groove segment of groove 404 of FIG. 5, showing asmall differential segment 410 of groove 404. At a given radius R,groove 404 has a given width W and a central axis A that forms an angleθ (“groove angle”) with respect to a radial line L connecting the originO to the given radius R. In some aspects of these embodiments, thechemical mechanical polishing pad has a texture comprising a groovepattern, wherein CF remains within 25%, preferably within 10%, morepreferably within 5% of its average value as a function of the polishingpad radius R in an area extending from an outer radius R_(O) of thepolishing surface a majority distance to origin O. In some aspects ofthese embodiments, the chemical mechanical polishing pad has a texturecomprising a groove pattern, wherein CF remains within 25%, preferablywithin 10%, more preferably within 5% of its average value as a functionof polishing pad radius R in an area extending from base radius R_(B) toouter radius R_(O).

In some embodiments of the present invention, the method of producing achemical mechanical polishing pad, comprises: electrostatically spinningat least one liquid spinning composition through at least one spinneretto form spun fibers and collecting the spun fibers on a target toprovide an electrospun polishing layer having a polishing surface,wherein the polishing surface is adapted for polishing a semiconductorsubstrate. In some aspects of these embodiments, the method comprisescollecting randomly oriented spun fibers on the target to provide theelectrospun polishing layer. The process of electrostatically spinningcomprises the introduction of a liquid spinning composition into anelectric field, whereby the liquid spinning composition is caused toproduce fibers which tend to be drawn to a target. While being drawnfrom the liquid spinning composition, the fibers typically harden, whichmay involve cooling (e.g., systems in which the liquid spinningcomposition is normally a solid at room temperature), chemical hardening(e.g., systems in which the spun fibers are treated with a vapor or gasthat causes the spun fibers to harden), or evaporation of a solvent fromthe liquid spinning composition. The resultant spun fibers collected onthe target are typically later removed from the target. In some aspectsof these embodiments, the electrostatic field is generated by applyingan electrostatic potential across the target and the at least onespinneret during the electrostatic spinning operation of 5 to 1,000 kV;preferably 5 to 100 kV; more preferably 10 to 50 kV. Any appropriatemethod of producing the desired electrostatic potential can be employed.In some aspects of these embodiments, the target is maintained at groundpotential. In some aspects of these embodiments, the at least onespinneret is maintained at ground potential.

In some embodiments of the present invention, the method of producing achemical mechanical polishing pad, comprises: providing an electrospunpolishing layer having a polishing surface and a thickness (measured ina direction normal to the polishing surface) of ≧10 mils, wherein theelectrospun polishing layer is prepared by electrostatically spinning atleast one liquid spinning composition through at least one spinneretforming spun fibers and collecting the spun fibers randomly oriented ona target, wherein the at least one liquid spinning composition comprisesan organic material; and, incorporating a texture into the electrospunpolishing layer. In some aspects of these embodiments, texture isincorporated into the electrospun polishing layer using at least one ofchemical etching, laser ablation and machining.

In some embodiments of the present invention, the step of incorporatinga texture into the electrospun polishing layer comprises providing atleast one of (i) at least one groove and (ii) a plurality ofperforations into the electrospun polishing layer. In some aspects ofthese embodiments, the step of incorporating a texture into theelectrospun polishing layer comprises incorporating at least one groove,a plurality of perforations or a combination of both into theelectrospun polishing layer. In some aspects of these embodiments, themethod comprises incorporating at least one groove, a plurality ofperforations, or a combination of both into the electrospun polishinglayer using at least one of embossing, chemical etching, laser ablatingand machining. In some aspects of these embodiments, the machining isperformed using a device capable of both drilling and routing.

In some embodiments of the present invention, the method of producing achemical mechanical polishing pad, comprises: providing a target,wherein the target exhibits a textured surface; electrostaticallyspinning at least one liquid spinning composition through at least onespinneret to form spun fibers; and collecting the spun fibers in randomorientation on the target to provide an electrospun polishing layerhaving a polishing surface; wherein the electrospun polishing layerexhibits a texture, which is a negative of the textured surfaceexhibited by the target. In some aspects of these embodiments, thetextured surface exhibited by the target includes at least one of (i) atleast one groove and (ii) a plurality of pillars. In some aspects ofthese embodiments, the texture exhibited by the electrospun polishinglayer comprises at least one of (i) at least one groove and (ii) aplurality of pillars. In some aspects of these embodiments, the textureexhibited by the electrospun polishing layer comprises a groove patternas described hereinabove. In some aspects of these embodiments, theelectrospun polishing layer provided exhibits a polishing surface and athickness (measured in a direction normal to the polishing surface) of≧10 mils.

In some embodiments of the present invention, the method of producing achemical mechanical polishing pad further comprises: exposing theelectrospun polishing layer to a compressive force normal to thepolishing surface, thereby compressing the polishing layer reducing thethickness of the electrospun polishing layer and reducing the total voidspace within the electrospun polishing layer. In some aspects of theseembodiments, the method further comprises: heating at least a portion ofthe compressed electrospun polishing layer to a temperature above theglass transition temperature for at least one spun fiber compositionwithin the electrospun polishing layer; then cooling the heated portionof the compressed electrospun polishing layer, locking the compressedelectrospun polishing layer in the compressed state; and then removingthe compressive force.

In some embodiments of the present invention, the method of producing achemical mechanical polishing pad further comprises: dispersing a fillermaterial in the void spaces within the electrospun polishing layer. Insome aspects of these embodiments, the filler material at leastpartially fills the void spaces within the electrospun polishing layer.Filler materials suitable for use in these methods are as previouslydescribed hereinabove.

In some embodiments of the present invention, the method of producing achemical mechanical polishing pad, comprises: electrostatically spinningat least one liquid spinning composition through at least one spinneretto form spun fibers and collecting the spun fibers randomly oriented ona target to provide an electrospun polishing layer having a polishingsurface, wherein the target is a volume of a conductive liquid andwherein the polishing surface is adapted for polishing a semiconductorsubstrate. In some aspects of these embodiments, the method furthercomprises providing a volume of a conductive liquid to be used as thetarget, wherein the conductive liquid comprises at least one of aninorganic electrolyte, an organic electrolyte or a combination thereof.In some aspects of these embodiments, the conductive liquid is a polymerwhich is dissimilar from the liquid spinning composition from which theelectrospun fibers are formed. In some aspects of these embodiments, theconductive liquid comprises a conductive material selected frominorganic and organic filler. In some aspects of these embodiments, theconductive liquid comprises a carbonaceous material. In some aspects ofthese embodiments, the conductive liquid comprises carbon nanotubes. Insome aspects of these embodiments, the conductive liquid comprises athermoset or thermoplastic material. In some aspects of theseembodiments, the conductive liquid target is a curable composition. Insome aspects of these embodiments the conductive liquid target is acurable composition selected from thermally curable compositions,evaporatively curable compositions, photolytically curable compositions,chemically curable compositions and combinations thereof. In someaspects of these embodiments, the conductive liquid target is curedfollowing collection of the spun fibers.

In some embodiments of the present invention, the method of producing achemical mechanical polishing pad, comprises: electrostatically spinningat least one liquid spinning composition through at least one spinneretto form at least one of spun fibers and beads of material; andcollecting the spun fibers and beads of material on a target to providean electrospun polishing layer having a polishing surface, wherein thepolishing surface is adapted for polishing a semiconductor substrate. Insome aspects of these embodiments, the electrospun polishing layerformed primarily comprises beads of material (i.e., beads of materialcomprise ≧95 wt %, preferably ≧99 wt %, of the electrospun polishinglayer). In some aspects of these embodiments, the electrospun polishinglayer formed primarily comprises spun fibers (i.e., spun fibers comprise≧95 wt %, preferably ≧99 wt %, of the electrospun polishing layer). Insome aspects of these embodiments, the electrospun polishing layerformed comprises beads of material formed amongst spun fibers. In someaspects of these embodiments, the electrospun polishing layer formedcomprises beads of material formed along spun fibers to create a“necklace” like structure. In some aspects of these embodiments, theratio of beads of material to spun fibers, the size of the beads and thedegree to which the beads of material are formed amongst rather thanalong the spun fibers are selected to tailor the CMP performanceproperties of the electrospun polishing layer.

In some embodiments of the present invention, the method of producing achemical mechanical polishing pad, comprises: electrostatically spinningat least one liquid spinning composition through at least one spinneretto form spun fibers; varying at least one of the spinneret to targetdistance, spinneret bore cross-sectional shape, and spinneret borecross-sectional area during the electrostatic spinning; and collectingthe spun fibers randomly oriented on a target to provide an electrospunpolishing layer having a polishing surface; wherein the polishingsurface is adapted for polishing a semiconductor substrate.

In some embodiments of the present invention, the method of producing achemical mechanical polishing pad, comprises: electrostatically spinningat least one liquid spinning composition through at least one spinneretto form spun fibers; collecting the spun fibers on a target to providean electrospun polishing layer having a polishing surface; and providinga gas flow between the at least one spinneret and the target; whereinthe polishing surface is adapted for polishing a semiconductorsubstrate.

In some embodiments of the present invention, the method of polishing asemiconductor substrate, comprises: a) providing a chemical mechanicalpolishing pad comprising an electrospun polishing layer, wherein theelectrospun polishing layer has a thickness of ≧10 mils and wherein theelectrospun polishing layer has a polishing surface; b) providing asemiconductor substrate; and, c) creating dynamic contact between thepolishing surface and the semiconductor substrate to polish a surface ofthe semiconductor substrate. In some aspects of these embodiments, themethod further comprises: incorporating a texture into the electrospunpolishing layer. In some aspects of these embodiments, the methodfurther comprises: providing a polishing medium at an interface betweenthe polishing surface and the surface of the substrate. In some aspectsof these embodiments, the polishing surface exhibits a self renewingproperty such that steps (b) and (c) can be repeated multiple timeswithout a need for abrasive conditioning of the polishing surface.

Some embodiments of the present invention will now be described indetail in the following Examples.

The polishing pads used in the Examples were prepared using thefollowing procedures. A multihead electrospinning nozzle assembly asdepicted in FIG. 1 was used to prepare the electrospun polishing layers.In particular, the apparatus depicted in FIG. 1 comprised a four linenozzle assembly 10. The four line nozzle assembly 10 had four parallelheads (a first head 40, a second head 50, a third head 60, a fourth head70) with sixteen 19 gage single needle stainless steel dispensing tips20 and twenty-four 21 gage single needle stainless steel dispensing tips30 arranged thereon as depicted in FIG. 1. The second and third heads50, 60 were supplied with a liquid spinning composition to facilitateelectrospinning via a main feed line 80, which split into a second feed55 to the second head 50 and a third feed 62 to the third head 60. Thefirst head 40 was charged with liquid spinning composition via a firstconnection 45 between the first head 40 and the second head 50. Thefourth head 70 was charged with liquid spinning composition via a secondconnection 65 between the third head 60 and the fourth head 70.

The target used to produce the electrospun polishing layers used in theExamples was a copper plate sprayed with a release agent. The target wasset up to move in an elliptical motion having a 4″ major axis and a 2″minor axis at a speed of 0.1 inch/minute. The distance between thetarget and the multihead electrospinning nozzle assembly was set at 25cm and the potential difference between the spinnerets and the targetwas set at 32 kV. The liquid spinning composition used was a 14.5 wt %solids solution in N,N-dimethylformamide with 0.5 wt %polyethyleneglycol monoethyl ether. The solids comprised a mixture of 87wt % polyurethane blend and 13 wt % polyvinyl chloride. Theelectrospinning operation proceeded for 6.125 days to prepare eachelectrospun polishing layer. The electrospun polishing layers formedcomprised a nonwoven web of spun fibers in random orientation withdiameters of 100 to 2,000 nm. The electrospun polishing layers had athickness of 30 to 120 mils and a density of 0.44 g/cm³. FIG. 2 is a5,000× magnification, scanning electron micrograph of a electrospunpolishing layer so formed. FIG. 3 is a 1,000× magnification, scanningelectron micrograph of an electrospun polishing layer so formed. Theelectrospun polishing layers were then laminated to an SP2150 poroussubpad material (a polyurethane roll-good available from Rohm and HaasElectronic Materials CMP Inc.) using a pressure sensitive adhesive toprovide stacked chemical mechanical polishing pads. The polishingsurfaces of the electrospun polishing layers were grooved withconcentric circular grooves having a 20 mil width, a 30 mil depth and a120 mil pitch. The stacked, grooved chemical mechanical polishing padswere then die cut to provide a substantially circular chemicalmechanical polishing pads having an average diameter of 20 inches, whichpads were then used to perform the polishing tests described in theExamples 1-15.

EXAMPLES 1-15

The polishing tests were performed using 200 mm blanket wafers,specifically (A) TEOS dielectric wafers (Examples 1-6); (B) Coral® low-kdielectric, carbon-doped oxide film wafers (available from NovellusSystems, Inc.) (Examples 7-9); (C) tantalum nitride wafers (Examples10-12); and (D) electroplated copper wafers (Examples 13-15). AStrasbaugh nSpire™ CMP system model 6EC rotary type polishing platformwas used to polish all of the blanket wafers in the Examples. Thepolishing conditions used in all of the Examples included a platen speedof 93 rpm; a carrier speed of 87 rpm; with a polishing medium flow rateof 200 ml/min and a downforce of 1 or 1.5 psi (as indicated in Table 1).The polishing medium used in all of the Examples was ACuPlane LK393C4(an advanced Barrier CMP Slurry available from RHEM). Removal rates foreach of the polish experiments are provided in Table 1. Note that theremoval rates were calculated from the before and after polish filmthickness on the blanket wafers. Specifically, the removal rates for theCoral® wafers and the TEOS wafers were determined using a SpectraFX 200optical thin-film metrology system available from KLA-Tencor. Theremoval rates for the electroplated copper wafers and the tantalumnitride wafers were determined using a ResMap model 168 four point proberesistivity mapping system from Creative Design Engineering, Inc.

TABLE 1 TEOS Coral ® Down removal removal Tantalum Nitride Copper Ex.Force rate rate removal rate removal rate No. (psi) (Å/min) (Å/min)(Å/min) (Å/min) 1 1 81 2 1 123 3 1 145 4 1 146 5 1.5 207 6 1.5 230 7 1122 8 1.5 173 9 1.5 173 10 1 155 11 1.5 230 12 1.5 227 13 1 68 14 1.5134 15 1.5 115

1. A chemical mechanical polishing pad for polishing semiconductorsubstrates, comprising: an electrospun polishing layer; wherein theelectrospun polishing layer has a polishing surface that is adapted forpolishing a semiconductor substrate.
 2. The chemical mechanicalpolishing pad of claim 1, wherein the electrospun polishing layer has athickness of ≧10 mils.
 3. The chemical mechanical polishing pad of claim1, wherein the electrospun polishing layer has an average pore size ≦5μm.
 4. The chemical mechanical polishing pad of claim 1, wherein theelectrospun polishing layer is formed of electrostatically spun organicfibers, wherein the fibers have a diameter of 100 to 2,000 nm.
 5. Thechemical mechanical polishing pad of claim 1, wherein the polishingsurface of the electrospun polishing layer exhibits a texture tofacilitate polishing of the semiconductor substrate.
 6. A method forproducing a chemical mechanical polishing pad, comprising:electrostatically spinning at least one liquid spinning compositionthrough at least one spinneret to form spun fibers and collecting thespun fibers on a target to provide an electrospun polishing layer havinga polishing surface, wherein the polishing surface is adapted forpolishing a semiconductor substrate.
 7. The method of claim 6, whereinthe target is a volume of a conductive liquid.
 8. A method of polishinga semiconductor substrate, comprising: a) providing a chemicalmechanical polishing pad comprising an electrospun polishing layer,wherein the electrospun polishing layer has a thickness of ≧10 mils andwherein the electrospun polishing layer has a polishing surface; b)providing a semiconductor substrate; and, c) creating dynamic contactbetween the polishing surface and the semiconductor substrate to polisha surface of the semiconductor substrate.
 9. The method of claim 8,wherein the polishing surface is self renewing and steps (b) and (c) arerepeated multiple times without a need for abrasive conditioning of thepolishing surface.